Process for the preparation of polyolefins

ABSTRACT

Polyolefins with a molecular weight distribution M w  /M n  ≧3.0, which may be monomodal, bimodal or multimodal, can be obtained by polymerization or copolymerization of olefins with a catalyst system consisting of an aluminoxane and a transition metal component (metallocene), in which the transition metal component consists of at least one zirconocene of the formula I and at least one zirconocene of the formula Ia ##STR1## or alternatively of at least 2 zirconocenes of the formula I.

This is a continuation of Ser. No. 08/312,718 filed on Sep. 27, 1994,now abandoned.

The invention relates to a process for the preparation of polyolefinshaving a wide molecular weight distribution and high molecular weight.

It is known that metallocene catalysts together with aluminoxanes canpolymerize olefins into polyolefins having a narrow molecular weightdistribution (M_(w) /M_(n) of 2-3) (J. Polym. Sci, Pol. Chem. Ed. 23(1985) 2117; EP-A 302 424). Polyolefins of this type having a narrowmolecular weight distribution are suitable, for example, forapplications in precision injection moulding, general injection mouldingand fibre production. For numerous applications such as thermoforming,extrusion, blow moulding and the production of polyolefin foams andfilms, wider or bimodal molecular weight distribution is required.

It was suggested that for polyethylene such products could be obtainedby using two or more metallocene catalysts in polymerization (EP-A 128045); the systems described are however achiral catalysts and in thepolymerization of propene would yield atactic polypropylene. Atacticpolypropylene is however unsuitable as an engineering polymer.

The preparation of stereo block polypropylene with M_(w) /M_(n) of 13-15is known from DE-OS 3 640 924. These catalyst systems are likewiseunsuitable for forming polyolefins of high tacticity. Furthermore, thelevels of metallocene activity and molecular weight of the polymerproducts achievable at the industrially relevant polymerizationtemperatures are too low. Moreover, the suggested catalysts yield onlyatactic polymer at such polymerization temperatures.

In EP-A 310 734, catalyst systems consisting of a mixture of a hafnoceneand a zirconocene are suggested for the preparation of polypropylene.The products have wide to bimodal distribution with M_(w) /M_(n) of 3.7to 10.3.

According to EP-A 355 439, by using only one hafnocene catalyst at aspecified polymerization temperature, polypropylene having a widemolecular weight distribution is obtained.

Syndiotactic polypropylene having a wide molecular weight distribution(M_(w) /M_(n) up to 6.4) prepared by using a hafnocene is described inEP-A 387 691.

The disadvantages common to these processes are the excessive costs ofthe hafnium catalysts for industrial applications and their lowpolymerization activity, which makes thorough, cost-intensive cleaningof the prepared polymer necessary to remove catalyst residues (highresidual ash content).

In EP-A-O 516 018, the use of two zirconocenes to prepare polymershaving a wide molecular weight distribution is described. Themetallocenes described there, however, have deficiencies inpolymerization activity and in achievable molecular weight level at theindustrially relevant polymerization temperatures of over 50° C.

Accordingly, the object was to find a catalyst system and a process bymeans of which polyolefins having a wide, bimodal or multimodaldistribution could be prepared and which avoided the known disadvantagesof state-of-the-art-technology.

In particular, the new process had to avoid the high residual ashcontent arising from low polymerization activity and enable thepreparation of high-molecular-weight polymer moulding materials such asare required, for example, for production of compression moulded sheets,extruded sheets and pipes, and blow mouldings of all sizes. Preferredapplications for such polymers with low flowability are, for example,blow moulded cases with integral hinges, skin packaging, sheet materialfor die punching, hot water tanks, wastewater and hot water pipes,pressure pipes, filter plates, heat exchangers, solid rods or automotiveparts such as brake fluid reservoirs and radiator expansion tanks. Inthe films sector, these moulding materials are used for tear-resistantBOPP films.

Surprisingly, it was found that the disadvantages of state-of-the-arttechnology can be avoided by using a, catalyst system consisting of atleast two stereorigid zirconocenes, of which at least one hassubstituted indenyl ligands on the six-membered ring, and an aluminiumcompound as co-catalyst.

The invention thus relates to a process for the preparation of apolyolefin having a molecular weight distribution M_(w) /M_(n) ≧3.0,which may be monomodal, bimodal or multimodal, by polymerization orcopolymerization of an olefin of the formula R^(a) CH═CHR^(b), in whichR^(a) and R^(b) are identical or different and are a hydrogen atom or analkyl radical with 1 to 14 C atoms, or R^(a) and R^(b) may form a ringsystem together with the atoms connecting them, at a temperature of50°-200° C., at a pressure of 0.5 to 100 bar, in solution, in suspensionor in the gas phase, in the presence of a catalyst which consists of atransition metal component (metallocene) and an aluminoxane of theformula II ##STR2## for the linear type and/or formula III ##STR3## forthe cyclic type, in which the radicals R in formulae II and III may beidentical or different and are a C₁ -C₆ alkyl group, a C₁ -C₆fluoroalkyl group, a C₆ -C₁₈ aryl group, a C₁ -C₆ fluoroaryl group orhydrogen and n is an integer from 0 to 50, or, instead of thealuminoxane, a mixture of an aluminoxane of the formula II and/or theformula III with an AlR₃ compound, characterized by the fact that atleast one zirconocene of the formula I and at least one zirconocene ofthe formula Ia or alternatively at least 2 zirconocenes of the formula Iare used as the transition metal component, ##STR4## in which R¹ and R²are identical or different and are a hydrogen atom, a C₁ -C₁₀ alkylgroup, a C₁ -C₁₀ alkoxy group, a C₆ -C₁₀ aryl group, a C₆ -C₁₀ aryloxygroup, a C₂ -C₁₀ alkenyl group, a C₇ -C₄₀ arylalkyl group, a C₇ -C₄₀alkylaryl group, a C₈ -C₄₀ arylalkenyl group or a halogen atom,

R³ are hydrogen, a halogen atom, a C₁ -C₁₀ alkyl group, which may behalogenated, a C₆ -C₁₀ aryl group, a C₂ -C₁₀ alkenyl group, a C₇ -C₄₀arylalkyl group, a C₇ -C₄₀ alkyloxy group, a C₈ -C₄₀ arylalkenyl group,an --NR₂ ¹⁰, --OR¹⁰, --SR¹⁰, --OSiR₃ ¹⁰, --SiR₃ ¹⁰ or --PR₂ ¹⁰ radical,in which R¹⁰ is a halogen atom, a C₁ -C₁₀ alkyl group or a C₆ -C₁₀ arylgroup,

R⁴ are identical or different and are a hydrogen atom, a halogen atom, aC₁ -C₂₀ alkyl group, a C₁ -C₂₀ fluoroalkyl group, a C₆ -C₃₀ aryl group,a C₆ -C₃₀ fluoroaryl group, a C₁ -C₂₀ alkoxy group, a C₂ -C₂₀ alkenylgroup, a C₇ -C₄₀ arylalkyl group, a C₈ -C₄₀ arylalkenyl group, a C₇ -C₄₀alkylaryl group, an --NR₂ ¹⁰, --OR¹⁰, --SR¹⁰, --OSiR₃ ¹⁰, --SiR₃ ¹⁰ or--PR₂ ¹⁰ radical, in which R¹⁰ is a halogen atom, a C₁ -C₁₀ alkyl groupor a C₆ -C₁₀ aryl group, where at least one R⁴ radicals per indenyl ringis different from hydrogen, or two or more R⁴ radicals form a ringsystem with the atoms connecting them,

R⁵ and R⁶ are identical or different and are a halogen atom, a C₁ -C₁₀alkyl group, which may be halogenated, a C₆ -C₁₀ aryl group, a C₂ -C₁₀alkenyl group, a C₇ -C₄₀ arylalkyl group, a C₇ -C₄₀ alkyloxy group, a C₈-C₄₀ arylalkenyl group, an --NR₂ ¹⁰, --OR¹⁰, --SR¹⁰, --OSiR₃ ¹⁰, --SiR₃¹⁰ or --PR₂ ¹⁰ radical, in which R¹⁰ is a halogen atom, a C₁ -C₁₀ alkylgroup or a C₆ -C₁₀ aryl group,

R⁷ is ##STR5## ═BR¹¹, ═AlR¹¹, --Ge--, --Sn--, --O--, --S--, ═SO, ═SO₂,═NR¹¹, ═CO, ═PR¹¹ or P(O)R¹¹, where

R¹¹, R¹² and R¹³ are identical or different and are a hydrogen atom, ahalogen atom, a C₁ -C₂₀ alkyl group, a C₁ -C₂₀ fluoroalkyl group, a C₆-C₃₀ aryl group, a C₆ -C₃₀ fluoroaryl group, a C₁ -C₂₀ alkoxy group, aC₂ -C₂₀ alkenyl group, a C₇ -C₄₀ arylalkyl group, a C₈ -C₄₀ arylalkenylgroup, a C₇ -C₄₀ alkylaryl group, or R¹¹ and R¹² or R¹¹ and R¹³ eachform a ring with the atoms connecting them,

M¹ is silicon, germanium or tin,

R⁸ and R⁹ are identical or different and are a hydrogen atom, a halogenatom, a C₁ -C₂₀ alkyl group, a C₁ -C₂₀ fluoroalkyl group, a C₆ -C₃₀ arylgroup, a C₆ -C₃₀ fluoroaryl group, a C₁ -C₂₀ alkoxy group, a C₂ -C₂₀alkenyl group, a C₇ -C₄₀ arylalkyl group, a C₈ -C₄₀ arylalkenyl group, aC₇ -C₄₀ alkylaryl group, or R⁸ and R⁹ each form a ring with the atomsconnecting them,

R¹⁴ and R¹⁵ are identical or different and are a monocyclic orpolycyclic hydrocarbon radical, which may form a sandwich structure withthe zirconium atom and

m and n are identical or different and are zero, 1 or 2, with m plus nbeing equal to zero, 1 or 2.

Alkyl denotes linear or branched alkyl. Halogen (halogenated) meansfluorine, chlorine, bromine or iodine, preferably fluorine or chlorine.

R¹ and R² are identical or different and are a hydrogen atom, a C₁ -C₁₀,preferably C₁ -C₃, alkyl group, a C₁ -C₁₀, preferably C₁ -C₃, alkoxygroup, a C₆ -C₁₀, preferably C₆ -C₈, aryl group, a C₆ -C₁₀, preferablyC₆ -C₈, aryloxy group, a C₂ -C₁₀, preferably C₂ -C₄, alkenyl group, a C₇-C₄₀, preferably C₇ -C₁₀, arylalkyl group, a C₇ -C₄₀, preferably C₇-C₁₂, alkylaryl group, a C₈ -C₄₀, preferably C₈ -C₁₂, arylalkenyl groupor a halogen atom, preferably chlorine.

R³ is hydrogen, a halogen atom, preferably a fluorine, chlorine orbromine atom, a C₁ -C₁₀, preferably C₁ -C₄, alkyl group, which may behalogenated, a C₆ -C₁₀, preferably C₆ -C₈, aryl group, a C₂ -C₁₀,preferably C₂ -C₄, alkenyl group, a C₇ -C₄₀, preferably C₇ -C₁₀,arylalkyl group, a C₇ -C₄₀, preferably C₇ -C₁₂, alkylaryl group, a C₈-C₄₀, preferably C₈ -C₁₂, arylalkenyl group, an --NR₂ ¹⁰, --SR¹⁰,--OSiR₃ ¹⁰, --OR¹⁰, --SiR₃ ¹⁰ or --PR₂ ¹⁰ radical, where R¹⁰ is ahalogen atom, preferably a chlorine atom, or a C₁ -C₁₀, preferably C₁-C₃, alkyl group or C₆ -C₁₀, preferably C₆ -C₈, aryl group, with R³ ashydrogen being specially preferred.

The R⁴ radicals are identical or different and are a hydrogen atom, ahalogen atom, a C₁ -C₂₀, preferably C₁ -C₁₀, alkyl group, a C₁ -C₂₀,preferably C₁ -C₁₀, fluoroalkyl group, a C₆ -C₃₀, preferably C₆ -C₂₀,aryl group, a C₆ -C₃₀, preferably C₆ -C₂₀, fluoroaryl group, a C₁ -C₂₀,preferably C₁ -C₁₀, alkoxy group, a C₂ -C₂₀, preferably C₂ -C₁₀, alkenylgroup, a C₇ -C₄₀, preferably C₇ -C₂₀, arylalkyl group, a C₈ -C₄₀,preferably C₈ -C₂₂, arylalkenyl group or a C₇ -C₄₀, preferably C₇ -C₂₂,alkylaryl group, an --NR₂ ¹⁰, --SR¹⁰, --OSiR₃ ¹⁰, --OR¹⁰, --SiR₃ ¹⁰ or--PR₂ ¹⁰ radical, in which R¹⁰ is a halogen atom, preferably a chlorineatom, or a C₁ -C₁₀, preferably C₁ -C₃, alkyl group or C₆ -C₁₀,preferably C₆ -C₈, aryl group, where at least one R⁴ radicals perindenyl ring is different from hydrogen, or two or more R⁴ radicals forma ring system with the atoms connecting them, which is mono- orpolycyclic.

R⁵ and R⁶ are identical or different and are a halogen atom, preferablya fluorine, chlorine or bromine atom, a C₁ -C₁₀, preferably C₁ -C₄,alkyl group, which may be halogenated, a C₆ -C₁₀, preferably C₆ -C₈,aryl group, a C₂ -C₁₀, preferably C₂ -C₄, alkenyl group, a C₇ -C₄₀,preferably C₇ -C₁₀, arylalkyl group, a C₇ -C₄₀, preferably C₇ -C₁₂,alkylaryl group, a C₈ -C₄₀, preferably C₈ -C₁₂, arylalkenyl group, an--NR₂ ¹⁰, --SR¹⁰, OSiR₃ ¹⁰, --OR¹⁰, --SiR₃ ¹⁰ or --PR₂ ¹⁰ radical, whereR¹⁰ is a halogen atom, preferably a chlorine atom, or a C₁ -C₁₀,preferably C₁ -C₃, alkyl group or C₆ -C₁₀, preferably C₆ -C₈, arylgroup.

R⁷ is ##STR6## ═BR¹¹, ═AlR¹¹, --Ge--, --Sn--, --O--, --S--, ═SO, ═SO₂,═NR¹¹, ═CO, ═PR¹¹ or P(O)R¹¹, where

R¹¹, R¹² and R¹³ are identical or different and are a hydrogen atom, ahalogen atom, a C₁ -C₂₀, preferably C₁ -C₁₀, alkyl group, a C₁ -C₂₀,preferably C₁ -C₁₀, fluoroalkyl group, a C₆ -C₃₀, preferably C₆ -C₂₀,aryl group, a C₆ -C₃₀, preferably C₆ -C₂₀, fluoroaryl group, a C₁ -C₂₀,preferably C₁ -C₁₀, alkoxy group, a C₂ -C₂₀, preferably C₂ -C₁₀, alkenylgroup, a C₇ -C₄₀, preferably C₇ -C₂₀, arylalkyl group, a C₈ -C₄₀,preferably C₈ -C₂₂, arylalkenyl group or a C₇ -C₄₀, preferably C₇ -C₂₂,alkylaryl group, or R¹¹ and R¹² or R¹¹ and R¹³ each form a ring with theatoms connecting them.

M¹ is silicon, germanium or tin, preferably silicon and germanium.

R⁷ is preferably ═CR¹¹ R¹², ═SiR¹¹ R¹², ═GeR¹¹ R¹², --O--, --S--, ═SO,═PR¹¹ or ═P(O)R¹¹.

R⁸ and R⁹ are identical or different and are a hydrogen atom, a halogenatom, a C₁ -C₂₀, preferably C₁ -C₁₀, alkyl group, a C₁ -C₂₀, preferablyC₁ -C₁₀, fluoroalkyl group, a C₆ -C₃₀, preferably C₆ -C₂₀, aryl group, aC₆ -C₃₀, preferably C₆ -C₂₀, fluoroaryl group, a C₁ -C₂₀, preferably C₁-C₁₀, alkoxy group, a C₂ -C₂₀, preferably C₂ -C₁₀, alkenyl group, a C₇-C₄₀, preferably C₇ -C₂₀, arylalkyl group, a C₈ -C₄₀, preferably C₈-C₂₂, arylalkenyl group or a C₇ -C₄₀, preferably C₇ -C₂₂, alkylarylgroup or R⁸ and R⁹ each form a ring with the atoms connecting them.

m and n are identical or different and are zero, 1 or 2, preferably zeroor 1, with m plus n being equal to zero, 1 or 2, preferably zero or 1.

R¹⁴ and R¹⁵ are preferably fluorenyl, indenyl and cyclopentadienyl andthese basic structures may carry additional substituents in the meaningof R⁴. In the case of an indenyl basic structure, the six-membered ringmay not however contain any substituents which are different fromhydrogen if the five-membered ring in the 2 position (adjacent to thebridge --(CR⁸ R⁹)_(m) --R⁷ --(CR⁸ R⁹)--) carries a radical R⁵ or R⁶which is different from hydrogen.

Thus the specially preferred metallocenes are those in which in formulaI, R¹ and R² are identical or different and are methyl or chlorine, R³is hydrogen and R⁷ is a radical ##STR7## with n plus m being equal tozero or 1; in particular such compounds of formula I, in which theindenyl radicals are substituted in the 2,4-, 2,5-, 2,4,6-, 2,4,5-,2,4,5,6-, and 2,5,6- positions, such as eg:

dimethylsilanediylbis(2-methyl-4-phenyl-1-indenyl )ZrCl₂

phenyl(methyl)silanediylbis(2-methyl-4-phenyl-1-indenyl)ZrCl₂

dimethylsilanediylbis(2-methyl-4-(1-naphthyl)-1-indenyl)ZrCl₂

dimethylsilanediylbis(2-methyl-4-(2-naphthyl)-1-indenyl)ZrCl₂

dimethylsilanediylbis(2-ethyl-4-(1-naphthyl)-1-indenyl)ZrCl₂

dimethylsilanediylbis(2-methyl-4,6-diisopropyl-1-indenyl)ZrCl₂

dimethylsilanediylbis(2,4,6-trimethyl-1-indenyl)ZrCl₂

phenyl(methyl)silanediylbis(2-methyl-4,6-diisopropyl-1-indenyl)ZrCl₂

phenyl(methyl)silanediylbis(2,4,6-trimethyl-1-indenyl)ZrCl₂

1,2-ethanediylbis(2-methyl-4,6-diisopropyl-1-indenyl)ZrCl₂

1,2-butanediylbis(2-methyl-4,6-diisopropyl-1-indenyl)ZrCl₂

dimethylsilanediylbis(2-methyl-4-ethyl-1-indenyl)ZrCl₂

dimethylsilanediylbis(2-methyl-4-isopropyl-1-indenyl)ZrCl₂

dimethylsilanediylbis(2-methyl-4-t-butyl-1-indenyl)ZrCl₂

phenyl(methyl)silanediylbis(2-methyl-4-isopropyl-1-indenyl)ZrCl₂

dimethylsilanediylbis(2-ethyl-4-methyl-1-indenyl)ZrCl₂

dimethylsilanediylbis(2,4-dimethyl-1-indenyl)ZrCl₂

dimethylsilanediylbis(2-methyl-4-ethyl-1-indenyl)ZrCl₂

dimethylsilanediylbis(2-methyl-e-acenaphth-1-indenyl)ZrCl₂

phenyl(methyl)silanediylbis(2-methyl-4,5-benzo-1-indenyl)ZrCl₂

phenyl(methyl)silanediylbis(2-methyl-α-acenaphth-1-indenyl)ZrCl₂

1,2-ethanediylbis(2-methyl-4,5-benzo-1-indenyl)ZrCl₂

1,2-butanediylbis(2-methyl-4,5-benzo-1-indenyl)ZrCl₂

dimethylsilanediylbis(2-methyl-4,5-benzo-1-indenyl)ZrCl₂

1,2-butanediylbis(2-ethyl-4-phenyl-1-indenyl)ZrCl₂

dimethylsilanediylbis(2-ethyl-4-Phenyl-1-indenyl)ZrCl₂

dimethylsilanediylbis(2-methyl-5-isobutyl-1-indenyl)ZrCl₂

phenyl(methyl)silanediylbis(2-methyl-5-isobutyl-1-indenyl)ZrCl₂

dimethylsilanediylbis(2-methyl-5-t-butyl-1-indenyl)ZrCl₂

dimethylsilanediylbis(2,5,6-trimethyl-1-indenyl)ZrCl₂

and the compounds listed in the examples.

The specially preferred metallocenes of formula Ia are those in which

R¹ and R² are identical or different and are methyl or chlorine,

R⁷ is a radical ##STR8## n+m is equal to zero or 1 and R¹⁴ and R¹⁵ areidentical or different and are fluorenyl, indenyl or a substitutedcyclopentadienyl. Highly preferred compounds of the formula Ia are thosecompounds listed in the examples.

Special importance is thus attached to(±)-phenyl(methyl)silyl-(indenyl)₂ zirconium dichloride,diphenylmethylene(9-fluorenyl)(cyclopentadienyl) zirconium dichloride,phenyl(methyl)methylene(9-fluorenyl)(cyclopentadienyl)zirconiumdichloride, isopropylidene(9-fluorenyl)(cyclopentadienyl)zirconiumdichloride, (±)-dimethylsilyl(2,3,5-trimethyl-1-cyclopentadienyl)₂zirconium dichloride, (±)-dimethylsilyl(indenyl)₂ zirconium dichloride,(±)-dimethylgermyl(indenyl)₂ zirconium dichloride,(±)-dimethylsilyl(indenyl)₂ zirconium dimethyl,(±)-phenyl(vinyl)silyl(indenyl)₂ zirconium dichloride,(±)-phenyl(vinyl)silyl(indenyl)₂ zirconium dimethyl, ##STR9##(±)-dimethylsilyl (2,4-dimethylcyclopentadienyl)₂ zirconium dichloride,(±)-diphenylsilyl (2,4-dimethyl-1-cyclopentadienyl)zirconium dichloride,(±)-isopropylidene(indenyl)₂ zirconium dichloride,(±)-dimethylsilyl(2-methyl-4,5,6,7-tetrahydro-1-indenyl)₂ zirconiumdichloride, (±)-ethylene(indenyl)₂ zirconium dichloride(±)-methylene(3-t-butyl-1-cyclopentadienyl)₂ zirconium dichloride,(±)-dimethylsilyl(4,7-dimethyl-1-indenyl)₂ zirconium dichloride,(±)-dimethylsilyl(2-methyl-1-indenyl)₂ zirconiumdichloride, (±)-phenyl(methyl)silyl(2-methyl-1-indenyl)zirconium dichloride, (±)-dimethylsilyl(2-ethyl-1-indenyl)₂ zirconium dichloride, (±)-dimethylsilyl(4,5-benzo-1-indenyl)₂ zirconium dichloride and (±)-dimethylsilyl(4-phenyl-1-indenyl)₂ zirconium dichloride.

Metallocenes with C_(s) symmetry (for example R¹¹ R¹²C(fluorenyl)-(cyclopentadienyl) zirconium dimethyl) may be used toproduce a syndiotactic component in the polyolefin.

The term C_(s) symmetry for the purposes of the present invention meansthat the relevant metallocenes have a plane of symmetry perpendicular tothe plane occupied by Zr, R¹ and R². The bisector of z R¹ --Zr--R² runsin this plane of symmetry. This consideration of symmetry is confined toa part of the zirconocene molecule, ie the bridge --(CR⁸ R⁹)_(n) --R⁷--(CR⁸ R⁹)_(m) -- is not taken into account. Furthermore, the term C_(s)symmetry should be understood in a formal or idealized way. For example,shifts in the part of the molecule mentioned, which can be caused by thebridge and are open only to structural elucidation, are omitted fromconsideration for the purposes of the present invention.

The chiral metallocenes are used as racemic compounds for the productionof highly isotactic polyolefins. However, the pure d or 1 form may alsobe used. With these pure stereoisomeric forms, an optically activepolymer can be produced. The meso form of the metallocenes shouldhowever be separated off, since the polymerization-active centre (themetal atom) in these compounds is no longer chiral because ofmirror-image symmetry on the central metal and can therefore not producea highly isotactic polymer. If the meso form is not separated off,atactic polymer is obtained alongside isotactic polymer. For certainapplications--flexible mouldings, for example--this can be perfectlydesirable.

Separation of the stereoisomers is known in principle.

Metallocenes I and Ia may be prepared according to the followingreaction principle: ##STR10## (see Journal of Organomet. chem. (1985)63-67 and EP-A 320762).

Selection of metallocenes for the polymerization of olefins having wideor multimodal molecular weight distribution can be accomplished bycarrying out a test polymerization for each metallocene.

In this process, the olefin is polymerized into a polyolefin and itsaverage molecular weight M_(w) and its molecular weight distributionM_(w) /M_(n) are determined by gel permeation chromatography. Dependingon the required molecular weight distribution, the metallocenes are thencombined.

By including data on polymerization activity, it is possible withcomputer simulation of the combined gel permeation curves to obtain anyrequired molecular weight distribution through the types of metallocenesused and their quantity ratios.

The number of zirconocenes to be used in the process according to theinvention is preferably 2 or 3, in particular 2. However, a largernumber of different zirconocenes (eg 4 or 5) of formulas I and Ia mayalso be used.

By including data on polymerization activity and molecular weight atdifferent polymerization temperatures, in the presence of hydrogen as amolecular weight regulator or in the presence of comonomers, thecomputer simulation model can be further refined and the applicabilityof the process according to the invention further improved.

An aluminoxane of the formula II and/or III is used as the cocatalyst,with n being an integer from 0-50, preferably 10-35.

The radicals R are preferably identical and are methyl, isobutyl, phenylor benzyl, with methyl being specially preferred.

If the radicals R are different, then they are preferably methyl andhydrogen or alternatively methyl and isobutyl, with the content ofhydrogen or isobutyl being 0.01-40% (number of R radicals). Instead ofthe aluminoxane, a mixture consisting of aluminoxane and AlR₃ may beused as the cocatalyst in the polymerization, with R being as quotedabove or additionally in this case R may also be ethyl.

The aluminoxane may be produced in different ways by known processes.One of the methods is, for example, to react an aluminium hydrocarboncompound and/or a hybridoaluminium hydrocarbon compound with water(gaseous, solid, liquid or bound--for example as water ofcrystallization) in an inert solvent (such as toluene). To produce analuminoxane with different alkyl groups R, two different aluminiumtrialkyls (AlR₃ +AlR'₃), according to the required composition, arereacted with water (see S. Pasynkiewicz, Polyhedron 9 (1990) 429 andEP-A 302 424).

The exact structure of aluminoxanes II and III is unknown (A. R. Barronet al., J. Am. Chem. Soc. 115 (1993) 4971).

Irrespective of the method of preparation, a common characteristic ofall aluminoxane solutions is a changing content of unreacted aluminiumparent compound which is present in free form or as an adduct.

It is possible to preactivate the metallocenes either separately ortogether in a mixture with an aluminoxane of the formula (II) and/or(III) before their use in the polymerization reaction. Thissubstantially increases polymerization activity and improves grainmorphology.

Preactivation of the metallocenes is carried out in solution. Themetallocenes are preferably dissolved as a solid in a solution of thealuminoxane in an inert hydrocarbon. A suitable inert hydrocarbon is analiphatic or aromatic hydrocarbon. Preferably, toluene or a C₆ -C₁₀hydrocarbon is used.

The concentration of the aluminoxane in the solution ranges from about1% (w/w) up to the saturation limit, preferably from 5 to 30% (w/w), ineach case based on the total solution. The metallocenes may be used inthe same concentration but preferably they are used in an amount of 10⁻⁴-1 mol per mol aluminoxane. The preactivation time is 1 minute to 60hours, preferably 2 to 60 minutes. The preactivation process is carriedout at a temperature of -78° C. to 100° C., preferably 0° to 70° C.

The metallocenes may also be prepolymerized or applied onto a carrier.For prepolymerization, preferably the (or one of the) olefin(s) used inpolymerization is employed.

Suitable carriers are for example silica gels, aluminium oxides, solidaluminoxane, combinations of aluminoxane on a carrier such as silicagel, or other inorganic carrier materials. A suitable carrier materialis also a polyolefin powder in finely dispersed form.

Another possible form of the process according to the inventioncomprises using a salt-like compound of the formula R_(X) NH_(4-X) BR'₄or the formula R₃ PHBR'₄ as the cocatalyst instead of or as well as analuminoxane. In this compound, x=1, 2 or 3, R=alkyl or aryl, identicalor different, and R'=aryl, which may also be fluorinated or partlyfluorinated. In this case the catalyst consists of the reaction productof the metallocenes with one of the named compounds (see EP-A 277 004).

To remove catalyst poisons present in the olefin, cleaning with analuminium alkyl, for example AlMe₃ or AlEt₃, is an advantage. Thiscleaning can take place in the polymerization system itself or theolefin may be brought into contact with the aluminium compound before itis added to the polymerization system and then separated off again.

The polymerization or copolymerization is carried out in the knownmanner in solution, in suspension or in the gas phase, continuously orbatchwise, in one or more stages at a temperature of 50° to 200° C.,preferably 50° to 100° C. The olefins which are polymerized orcopolymerized are those of the formula R^(a) --CH═CH--R^(b). In thisformula, R^(a) and R^(b) are identical or different and are a hydrogenatom or an alkyl radical with 1 to 14 C atoms. R^(a) and R^(b) may alsoform a ring with the C atoms connecting them. Examples of olefins ofthis type are ethylene, propylene, 1-butene, 1-hexene,4-methyl-1-pentene, 1-octene, norbornene or norbornadiene. Inparticular, propylene and ethylene are polymerized.

If necessary, hydrogen is added as a molecular weight regulator. Thedifferent hydrogen sensitivity of the metallocenes, and the possibilityof altering the amount of hydrogen during polymerization can lead to afurther desired spread of the molecular weight distribution.

The total pressure in the polymerization system is 0.5 to 100 bar.Preferably, the polymerization is carried out in the pressure range of 5to 64 bar, which is of particular industrial relevance.

The metallocenes are used in a concentration, relative to the transitionmetal, of 10⁻³ to 10⁻⁸, preferably 10⁻⁴ to 10⁻⁷, mol of transition metalper dm³ of solvent or per dm³ of reactor volume. The aluminoxane or thealuminoxane/AlR₃ mixture is used in a concentration of 10⁻⁵ to 10⁻¹ mol,preferably 10⁻⁴ to 10⁻² mol, per dm³ of solvent or per dm³ of reactorvolume. However, in principle, higher concentrations are also possible.

If the polymerization is carried out as suspension or solutionpolymerization, an inert solvent customary for the Ziegler low-pressureprocess is used. For example, the polymerization is carried out in analiphatic or cycloaliphatic hydrocarbon; examples of such a hydrocarbonare butane, pentane, hexane, heptane, decane, isooctane, cyclohexane,methylcyclohexane.

Furthermore, a naphtha or hydrogenated diesel oil fraction can be used.Toluene is also usable. Preferably, the polymerization is carried out inthe liquid monomer.

If inert solvents are used, the monomers are metered in as a gas or aliquid.

The duration of the polymerization is as desired, since the catalystsystem to be used according to the invention shows only a smalltime-dependent drop in polymerization activity.

The process according to the invention is characterized by the fact thatthe metallocenes described exhibit very high polymerization activity inthe industrially relevant temperature range between 50° and 100° C.,producing polymers with wide, bimodal or multimodal molecular weightdistribution, very high molecular weight, high stereospecificity andgood grain morphology. The metallocene activity at a polymerizationtemperature of 50°-60° C. is >140 kg polymer/g catalyst ×hour,preferably >160 kg polymer/g catalyst ×hour. At polymerizationtemperatures >60°C., the metallocene activity is over 350, preferablyover 400 kg polymer/g catalyst ×hour. At polymerization temperatures of50°-60° C., the polymers according to the invention have a viscositynumber >260, preferably >360 cm³ /g, at polymerization temperatures >60°C., the viscosity number is over 200, preferably over 260 cm³ /g.Accordingly, the molecular weight M_(w) at polymerization temperaturesabove 60° C. is greater than 200 000 g/mol. M_(w) /M_(n) is ≧3.0,preferably ≧4.0. M_(w) /M_(n) is preferably <50, especially preferably<30.

The polymers according to the invention are particularly suitable forthe production of compression moulded sheets, extruded sheets and pipes,and blow mouldings of all sizes. Preferred applications for suchpolymers with low flowability are, for example, blow moulded cases withintegral hinges, skin packaging, sheet material for die punching, hotwater tanks, wastewater and hot water pipes, pressure pipes, filterplates, heat exchangers, solid rods or automotive parts such as brakefluid reservoirs and radiator expansion tanks. In the films sector,these moulding materials are used for tear-resistant BOPP films.

The following examples are intended to illustrate the invention in moredetail. The symbols have the following meanings:

VN=viscosity number in cm³ /g

M_(w) =average molecular weight in g/mol determined by gel

M_(w) /M_(n) =molecular weight dispersity permeation chromatography

II=isotactic index (mm+1/2 mr) determined by ¹³ C-NMR spectroscopy

EXAMPLES 1-12

A dry 24 dm³ reactor was flushed with propylene and filled with 12 dm³of liquid propylene. 26 cm³ of a methylaluminoxane solution in toluene(corresponding to 35 mmol of Al, mean degree of oligomerization n=22)were then added, and the batch was stirred for 10 minutes at 30° C.

At the same time, the metallocenes provided for the polymerization weremixed (for quantities and metallocene compounds see table 1), dissolvedin 10 m³ of methylaluminoxane solution in toluene (13 mmol Al) and after2 minutes poured into the reactor.

Polymerization was carried out for 1 hour at the polymerizationtemperature quoted in table 1 and then the polymerization reaction wasstopped with 12 Ndm³ of CO₂ gas. The polymer was dried for 24 hours at80° C. in vacuo.

The results of the polymerization are shown in table 1, in whichMe=methyl.

                                      TABLE 1                                     __________________________________________________________________________                  Polym. temp.                                                                         Yield                                                                            Activity                                                                             VN  M.sub.w II                                 Metallocene mixture                                                                         (°C.)                                                                         (kg)                                                                              kgPP/gcatxh!                                                                        (cm.sup.3 g)                                                                      (g/mol)                                                                           M.sub.w M.sub.n                                                                   (%)                                                                              Ex.                             __________________________________________________________________________    1.5 mg (±)-Me.sub.2 Si(2-methyl-4-                                                       50     1.95                                                                             433.0  568 704 000                                                                           15.7                                                                              98.9                                                                             1                               phenyl-1-indenyl).sub.2 ZrCl.sub.2     bimodal                                3.0 mg (±)-Me.sub.2 Si(indenyl).sub.2 -                                    ZrCl.sub.2                                                                    1.1 mg (±)-Me.sub.2 Si(2-methyl-4-                                                       60     1.80                                                                             142.8  560 764 000                                                                           6.9 -- 2                               (1-naphthyl)-1-indenyl).sub.2 ZrCl.sub.2                                      11.5 mg Ph.sub.2 C(fluorenyl)-                                                (cyclopentadienyl)ZrCl.sub.2                                                  0.5 mg (±)-Me.sub.2 Si(2-methyl-4-                                                       70     1.96                                                                             356.4  315 435 000                                                                           4.5 -- 3                               (1-naphthyl)-1-indenyl).sub.2 ZrCl.sub.2                                      5.0 mg Me.sub.2 C(fluorenyl)(cyclo-                                           pentadienyl)ZrCl.sub.2                                                        5.0 mg (±)-Me.sub.2 Si(2-methyl-                                                         50     1.98                                                                             198.5  265 332 000                                                                           8.4 97.3                                                                             4                               4,6-diisopropyl-1-indenyl).sub.2 -                                            ZrCl.sub.2                                                                    5.0 mg (±)-Me.sub.2 Ge(indenyl).sub.2 -                                    ZrCl.sub.2                                                                    4.3 mg (±)-Ph(Me)Si(2,4,6-tri-                                                           50     1.44                                                                             160.0  260 265 500                                                                           14.5                                                                              89.5                                                                             5                               methyl-1-indenyl).sub.2 ZrCl.sub.2     bimodal                                4.7 mg (±)-Me.sub.2 C(indenyl).sub.2 -                                     ZrCl.sub.2                                                                    1.7 mg (±)-Me.sub.2 Si(2-methyl-4-                                                       50     1.78                                                                             169.5  265 305 000                                                                           9.4 98.4                                                                             6                               isopropyl-1-indenyl).sub.2 ZrCl.sub.2  bimodal                                8.8 mg (±)-Me.sub.2 Si(2,3,5-tri-                                          methyl-1-cyclopentadienyl).sub.2 -                                            ZrCl.sub.2                                                                    1.8 mg (±)-Me.sub.2 Si(2-methyl-                                                         70     2.35                                                                             208.0  205 288 000                                                                           10.5                                                                              96.7                                                                             7                               4,5-benzo-1-indenyl).sub.2 ZrCl.sub.2  bimodal                                9.5 mg (±)-Me.sub.2 Si(2-methyl-4,5,                                       6,7-tetrahydro-1-indenyl).sub.2                                               ZrCl.sub.2                                                                    1.0 mg (±)-Ph(Me)Si(2-                                                                   70     1.92                                                                             384.0  207 205 500                                                                           8.4 97.3                                                                             8                               methyl-α-acenaphth-1-            bimodal                                indenyl).sub.2 ZrMe.sub.2                                                     4.0 mg (±)-Ph(vinyl)Si-                                                    (indenyl).sub.2 ZrMe.sub.2                                                    2.5 mg (±)-Me.sub.2 Si(2,5,6-                                                            55     1.02                                                                             255.0  276 289 500                                                                           6.4 96.4                                                                             9                               trimethyl-1-indenyl).sub.2 ZrCl.sub.2                                         1.5 mg (±)-Ph.sub.2 Si(2,4-                                                dimethyl-1-cyclopentadienyl).sub.2 -                                          ZrCl.sub.2                                                                    2.5 mg (±)-Me.sub.2 Si(2-methyl-                                                         70     1.95                                                                             488.0  203 265 000                                                                           10.5                                                                              97.9                                                                             10                              4,5-benzo-1-indenyl).sub.2 ZrCl.sub.2  bimodal                                1.5 mg (±)-Me.sub.2 Si(4,5-benzo-                                          1-indenyl).sub.2 ZrCl.sub.2                                                   0.7 mg (±)-Me.sub.2 Si(2-methyl-4-                                                       70     1.70                                                                             362.0  298 403 500                                                                           17.4                                                                              98.0                                                                             11                              phenyl-1-indenyl).sub.2 ZrCl.sub.2     bimodal                                4.0 mg (±)-Me.sub.2 Si(4-phenyl-1-                                         indenyl).sub.2 ZrCl.sub.2                                                     0.5 mg (±)-Me.sub.2 Si(2-methyl-4-                                                       70     2.07                                                                             376.5  345 496 000                                                                           8.5 96.8                                                                             12                              (1-naphthyl)-1-indenyl).sub.2 ZrCl.sub.2                                      5.0 mg (±)-Me.sub.2 Si(2,4,6-tri-                                          methyl-1-indenyl).sub.2 ZrCl.sub.2                                            0.5 mg (±)-Me.sub.2 Si(2-methyl-4-                                                       70     2.33                                                                             408.8  261 349 500                                                                           14.0                                                                              95.0                                                                             13                              phenyl-1-indenyl).sub.2 ZrCl.sub.2     multi-                                 4.4 mg (±)-Me.sub.2 Si(2,4,6-tri-   modal                                  methyl-1-indenyl).sub.2 ZrCl.sub.2                                            0.8 mg (±)-                                                                ethylidene(indenyl).sub.2 ZrCl.sub.2                                          __________________________________________________________________________

EXAMPLE 14

Example 1 was repeated but, before addition of the propylene, 3 Ndm³ ofhydrogen gas were introduced into the reactor.

5 2.85 kg of polymer were obtained and the metallocene activity was thus633.3 kg PP/g cat×h.

VN=319 cm³ /g; M_(w) =369 000 g/mol, M_(w) /M_(n) =12.0

The distribution was bimodal, II=99.1%.

EXAMPLE 15

Example 1 was repeated but in addition 100 g of ethylene were metered incontinuously during the polymerization.

2.24 kg of copolymer were obtained and the metallocene activity was thus497.8 kg copolymer/g cat×h.

VN=269 cm³ /g; M_(w) =305 000 g/mol, M_(w) /M_(n) =9.2.

4.2% (W/W) of ethylene was determined in the polymer by infraredspectroscopy.

EXAMPLE 16

Example 15 was repeated but 250 g of ethylene were added in one portionand this only after 30 minutes.

2.05 kg of block copolymer were obtained and the metallocene activitywas thus 455.6 kg copolymer/g cat×h.

VN=279 cm³ /g; M_(w) =268 000 g/mol, M_(w) /M_(n) =7.2.

The ethylene content as determined by infrared spectroscopy was 12.1%(W/W).

We claim:
 1. A metallocene mixture comprising at least two differentzirconocenes with at least one zirconocene of the formula I and at leastone zirconocene of the formula Ia ##STR11## in which R¹ and R² areidentical or different and are a hydrogen atom, a C₁ -C₁₀ to alkylgroup, a C₁ -C₁₀ alkoxy group, a C₆ -C₁₀ aryl group, a C₆ -C₁₀ aryloxygroup, a C₂ -C₁₀ alkenyl group, a C₇ -C₄₀ arylalkyl group, a C₇ -C₄₀alkylaryl group, a C₈ -C₄₀ arylalkenyl group or a halogen atom,R³ is ahydrogen atom, a halogen atom, a C₁ -C₁₀ alkyl group, which may behalogenated, a C₆ -C₁₀ aryl group, a C₂ -C₁₀ alkenyl group, a C₇ -C₄₀arylalkyl group, a C₇ -C₄₀ alkyloxy group, a C₈ -C₄₀ arylalkenyl group,an --NR₂ ¹⁰, --OR¹⁰, --SR¹⁰, --OSiR₃ ¹⁰, --SiR₃ ¹⁰ or --PR₂ ¹⁰ radical,in which R¹⁰ is a halogen atom, a C₁ -C₁₀ alkyl group or a C₆ -C₁₀ arylgroup, R⁴ are identical or different and are a hydrogen atom, a halogenatom, a C₁ -C₂₀ alkyl group, a C₁ -C₂₀ fluoroalkyl group, a C₆ -C₃₀ arylgroup, a C₆ -C₃₀ fluoroaryl group, a C₁ -C₂₀ alkoxy group, a C₂ -C₂₀alkenyl group, a C₇ -C₄₀ arylalkyl group, a C₈ -C₄₀ arylalkenyl group, aC₇ -C₄₀ alkylaryl group, an --NR₂ ¹⁰, --OR¹⁰, --SR¹⁰, --OSiR₃ ¹⁰, --SiR₃¹⁰ or --PR₂ ¹⁰ radical, in which R¹⁰ is a halogen atom, a C₁ -C₁₀ alkylgroup or a C₆ -C₁₀ aryl group, where at least one R⁴ radicals perindenyl ring is different from hydrogen, or two or more R⁴ radicals forma ring system with the atoms connecting them, R⁵ and R⁶ are identical ordifferent and are a halogen atom, a C₁ -C₁₀ alkyl group, which may behalogenated, a C₆ -C₁₀ aryl group, a C₂ -C₁₀ alkenyl group, a C₇ -C₄₀arylalkyl group, a C₇ -C₄₀ alkyloxy group, a C₈ -C₄₀ arylalkenyl group,an --NR₂ ¹⁰, --OR¹⁰, --SR¹⁰, --OSiR₃ ¹⁰, --SiR₃ ¹⁰ or --PR₂ ¹⁰ radical,in which R¹⁰ is a halogen atom, a C₁ -C₁₀ alkyl group or a C₆ -C₁₀ arylgroup, R⁷ is ##STR12## --Ge--, --Sn--, --O--, --S--, ═SO, ═SO₂, ═CO, orP(O)R¹¹, whereR¹¹, R¹² and R¹³ are identical or different and are ahydrogen atom, a halogen atom, a C₁ -C₂₀ alkyl group, a C₁ -C₂₀fluoroalkyl group, a C₆ -C₃₀ aryl group, a C₆ -C₃₀ fluoroaryl group, aC₁ -C₂₀ alkoxy group, a C₇ -C₄₀ arylalkyl group, a C₈ -C₄₀ arylalkenylgroup, a C₇ -C₄₀ alkylaryl group, or R¹¹ and R¹² or R¹¹ and R¹³ eachform a ring with the atoms connecting them, M¹ is tin, or R⁷ is##STR13## ═BR^(11'), ═AlR^(11'), ═NR^(11') or ═PR^(11') whereR^(11'),R^(12') and R^(13') are identical or different and are a hydrogen atom,a halogen atom, a C₁ -C₂₀ flouroalkyl group, a C₆ -C₃₀ fluoroaryl group,a C₁ -C₂₀ alkoxy group, a C₇ -C₄₀ arylalkyl group, a C₈ -C₄₀ arylalkenylgroup, a C₇ -C₄₀ alkylaryl group, or R^(11') and R^(12') or R^(11') andR^(13') each form a ring with the atoms connecting them, M^(1') issilicon or germanium, R⁸ and R⁹ are identical or different and are ahydrogen atom, a halogen atom, a C₁ -C₂₀ alkyl group, a C₁ -C₂₀fluoroalkyl group, a C₆ -C₃₀ aryl group, a C₆ -C₃₀ fluoroaryl group, aC₁ -C₂₀ alkoxy group, a C₂ -C₂₀ alkenyl group, a C₇ -C₄₀ arylalkylgroup, a C₈ -C₄₀ arylalkenyl group, a C₇ -C₄₀ alkylaryl group, or R⁸ andR⁹ each form a ring with the atoms connecting them, R¹⁴ and R¹⁵ areidentical or different and are unsubstituted or substitutedcyclopentadienyl which form a sandwich structure with the zirconium atomand optionally are substituted with the substituents defined in thedefinition of R⁴, m and n are identical or different and are zero, 1 or2, with m plus n being equal to zero, 1 or
 2. 2. The metallocene mixtureas claimed in claim 1 wherein the formula (Ia) is(±)-phenyl(methyl)silyl(indenyl)₂ zirconium dichloride, phenyl(methyl)methylene(9-fluorenyl)(cyclopentadienyl)zirconium dichloride,isopropylidene(9-fluorenyl)(cyclopentadienyl) zirconium dichloride,(±)-dimethylsilyl-1(2,3,5-trimethyl-1-cyclopentadienyl)₂ zirconiumdichloride, (±)-dimethylgermyl(indenyl)₂ zirconium dichloride,(±)-dimethylsilyl(indenyl)₂ zirconium dimethyl,(±)-phenyl(vinyl)silyl(indenyl)₂ zirconium dichloride,(±)-phenyl(vinyl)silyl(indenyl)₂ -zirconium dimethyl,(±)-dimethylsilyl(2,4-dimethylcyclopentadienyl)₂ zirconium dichloride,(±)-diphenylsilyl(2,4-dimethyl-1-cyclopentadienyl)zirconium dichloride,(±)-isopropylidene(indenyl)₂ -zirconium dichloride,(±)-dimethylsilyl(2-methyl-4,5,6,7-tetrahydro-1-indenyl)₂ zirconiumdichloride, (±)-ethylene(indenyl)₂ zirconium dichloride,(±)-methylene(3-t-butyl-1-cyclopentadienyl)₂ zirconium dichloride,(±)-dimethylsilyl(4,7-dimethyl-1-indenyl)₂ zirconium dichloride,(±)-dimethylsilyl(2-methyl-1-indenyl)₂ -zirconium dichloride,(±)-phenyl(methyl)silyl(2-methyl-1-indenyl)zirconium dichloride,(±)-dimethylsilyl(2-ethyl-1-indenyl)₂ zirconium dichloride,(±)-dimethylsilyl(4-phenyl-1-indenyl)₂ zirconium dichloride, or mixturesthereof.
 3. A metallocene mixture which is(±)-dimethylol(2-methyl-4-phenyl-1-indenyl)₂ ZrCl₂ and(±)-dimethylSi(indenyl)₂ -ZrCl₂ ;(±)-dimethylSi(2-methyl-4-(1-naphthyl)-1-indenyl)₂ ZrCl₂ anddiphenyl(fluorenyl)-(cyclopentadienyl)ZrCl₂ ;(±)-dimethylSi(2-methyl-4-(1-naphthyl)-1-indenyl)₂ ZrCl₂ anddimethyl-C(fluorenyl)(cyclopentadienyl)ZrCl₂ ;(±)-dimethylSi(2-methyl-4,6-diisopropyl-1-indenyl)₂ ZrCl₂ and(±)-dimethylGe(indenyl)₂ ZrCl₂ ;(±)-phenyl(methyl)Si(2,4,6-trimethyl-1-indenyl)₂ ZrCl₂ and(±)-dimethylC(indenyl)₂ -ZrCl₂ ;(±)-dimethylSi(2-methyl-4-isopropyl-1-indenyl)₂ ZrCl₂ and(±)-dimethylSi(2,3,5-trimethyl-1-cyclopentadienyl)₂ -ZrCl₂ ;(±)-dimethylSi(2-methyl-4,5-benzo-1-indenyl)₂ ZrCl₂ and(±)-dimethylSi(2-methyl-4,5,6,7-tetrahydro-1-indenyl)₂ -ZrCl₂ ;(±)-phenyl(methyl)Si(2-methyl-α-acenaphth-1-indenyl)₂ -Zr dimethyl and(±)-phenyl(vinyl)Si-(indenyl)₂ -Zr dimethyl;(±)-dimethylSi(2-5,6-trimethyl-1-indenyl)₂ -ZrCl₂ and (±)-phenyl₂Si(2,4-dimethyl-1-cyclopentadienyl)₂ -ZrCl₂ ;(±)-dimethylSi(2-methyl-4,5-benzo-1-indenyl)₂ -ZrCl₂ ; and(±)-dimethylSi(4,5-benzo-1-indenyl)₂ -ZrCl₂ ;(±)-dimethylSi(2-methyl-4-phenyl-1-indenyl)₂ -ZrCl₂ and(±)-dimethylSi(4-phenyl-1-indenyl)₂ -ZrCl₂ ;(±)-dimethylSi(2-methyl-4-(1-naphthyl)-1-indenyl)₂ -ZrCl₂ and(±)-dimethylSi-(2,4,6-tri-methyl-1-indenyl)₂ -ZrCl₂ ;(±)-dimethylSi(2-methyl-4-phenyl-1-indenyl)₂ ZrCl₂,(±)-dimethylSi(2,4,6-tri-methyl-1-indenyl)₂ ZrCl₂ or(±)-ethylidene(indenyl)₂ -ZrCl₂.
 4. A metallocene mixture comprising atleast two different zirconocenes with at least one zirconocene of thegroup I and at least one zirconocene of the formula Ia ##STR14## inwhich R¹ and R² are identical or different and are a hydrogen atom, a C₁-C₁₀ alkyl group, a C₁ -C₁₀ alkoxy group, a C₆ -C₁₀ aryl group, a C₆-C₁₀ aryloxy group, a C₂ -C₁₀ alkenyl group, a C₇ -C₄₀ arylalkyl group,a C₇ -C₄₀ alkylaryl group, a C₈ -C₄₀ arylalkenyl group or a halogenatom,R⁷ is ##STR15## --Ge--, --Sn--, --O--, --S--, ═SO, ═SO₂, ═CO, orP(O)R¹¹, whereR¹¹, R¹² and R¹³ are identical or different and are ahydrogen atom, a halogen atom, a C₁ -C₂₀ alkyl group, a C₁ -C₁₀fluoroalkyl group, a C₆ -C₃₀ aryl group, a C₆ -C₃₀ fluoroaryl group, aC₁ -C₂₀ alkoxy group, a C₇ -C₄₀ arylalkyl group, a C₈ -C₄₀ arylalkenylgroup, a C₇ -C₄₀ alkylaryl group, or R¹¹ and R¹² or R¹¹ and R¹³ eachform a ring with the atoms connecting them, M¹ is tin, or R⁷ is##STR16## ═BR^(11'), ═AlR^(11'), ═NR^(11') or ═PR^(11') whereR^(11'),R^(12') and R^(13') are identical or different and are a hydrogen atom,a halogen atom, a C₁ -C₂₀ fluoroalkyl group, a C₆ -C₃₀ fluoroaryl group,a C₁ -C₂₀ alkoxy group, a C₇ -C₄₀ arylalkyl group, a C₈ -C₄₀ arylalkenylgroup, a C₇ -C₄₀ alkylaryl group, or R^(11') and R^(12') or R^(11') andR^(13') each form a ring with the atoms connecting them, M^(1') issilicon or germanium, R⁸ and R⁹ are identical or different and are ahydrogen atom, a halogen atom, a C₁ -C₂₀ alkyl group, a C₁ -C₂₀fluoroalkyl group, a C₆ -C₃₀ aryl group, a C₆ -C₃₀ fluoroaryl group, aC₁ -C₂₀ alkoxy group, a C₂ -C₂₀ alkenyl group, a C₇ -C₄₀ arylalkylgroup, a C₈ -C₄₀ arylalkenyl group, a C₇ -C₄₀ alkylaryl group, or R⁸ andR⁹ each form a ring with the atoms connecting them, R¹⁴ and R¹⁵ areidentical or different and are unsubstituted or substitutedcyclopentadienyl which form a sandwich structure with the zirconium atomand optionally are substituted with the substituents defined in thedefinition of R₄, m and n are identical or different and are zero, 1 or2, with m plus n being equal to zero, 1 or 2 andthe zirconocene of thegroup I is dimethylsilanediylbis(2-methyl-4-phenyl-1-indenyl)ZrCl₂,phenyl(methyl)silanediylbis(2-methyl-4-phenyl-1-indenyl)ZrCl₂,dimethylsilanediylbis(2-methyl-4-(1-naphthyl)-1-indenyl)ZrCl₂,dimethylsilanediylbis(2-methyl-4-(2-naphthyl)-1-indenyl)ZrCl₂,dimethylsilanediylbis(2-ethyl-4-(1-naphthyl)-1-indenyl)ZrCl₂,dimethylsilanediylbis(2-methyl-4,6-diisopropyl-1-indenyl)ZrCl₂,dimethylsilanediylbis(2,4,6-trimethyl-1-indenyl)ZrCl₂,phenyl(methyl)silanediylbis(2-methyl-4,6-diisopropyl-1-indenyl)ZrCl₁₂,phenyl(methyl)silanediylbis(2,4,6-trimethyl-1-indenyl)ZrCl₂, 1.2-ethanediylbis(2-methyl-4,6-diisopropyl-1-indenyl)ZrCl₂,1,2-butanediylbis(2-methyl-4,6-diisopropyl-1-indenyl)ZrCl₂,dimethylsilanediylbis(2-methyl-4-ethyl-1-indenyl)ZrCl₂,dimethylsilanediylbis(2-methyl-4-disopropyl-1-indenyl)ZrCl₂,dimethylsilanediylbis(2-methyl-4-t-butyl-1-indenyl)ZrCl₂,phenyl(methyl)silanediylbis(2-methyl-4-isopropyl-1-indenyl)ZrCl₂,dimethylsilanediylbis(2-ethyl-4-methyl-1-indenyl)ZrCl₂,dimethylsilanediylbis(2,4-dimethyl-1-indenyl)ZrCl₂,dimethylsilanediylbis(2-methyl-4-ethyl-1-indenyl)ZrCl₂,dimethylsilanediylbis(2-methyl-α-acenaphth-1-indenyl)ZrCl₂,phenyl(methyl)silanediylbis(2-methyl-4,5-benzo-1-indenyl)ZrCl₂,phenyl(methyl)silanediylbis(2-methyl-α-acenaphth-1-indenyl)ZrCl₂1,2-ethanediylbis(2-methyl-4,5-benzo-1-indenyl)ZrCl₂,1,2-butanediylbis(2-methyl-4,5-benzo-1-indenyl)ZrCl₂,dimethylsilanediylbis(2-methyl1-4,5-benzo-1-indenyl)ZrCl₂,1,2-butanediylbis(2-ethyl-4-phenyl-1-indenyl)ZrCl₂,dimethylsilanediylbis(2-ethyl-4-phenyl-1-indenyl)ZrCl₂,dimethylsilanediylbis(2-methyl-5-isobutyl-1-indenyl)ZrCl₂,phenyl(methyl)silanediylbis(2-methyl-5-isobutyl-1-indenyl)ZrCl₂,dimethylsilanediylbis(2-methyl-5-t-butyl-1-indenyl)ZrCl₂, ordimethylsilanediylbis(2,5,6-trimethyl-1-indenyl)ZrCl₂.
 5. A metallocenemixture comprising at least two different zirconocenes with at least onezirconocene of the group I and at least one zirconocene of the group Iawherein the zirconocene of the group Iisdimethylsilanediylbis(2-methyl-4-phenyl-1-indenyl)ZrCl₂,phenyl(methyl)silanediylbis(2-methyl-4-phenyl-1-indenyl)ZrCl₂,dimethylsilanediylbis(2-methyl-4-(1-naphthyl)-1-indenyl)ZrCl₂,dimethylsilanediylbis(2-methyl-4-(2-naphthyl)-1-indenyl)ZrCl₂,dimethylsilanediylbis(2-ethyl-4-(1-naphthyl)-1-indenyl)ZrCl₂,dimethylsilanediylbis(2-methyl-4,6-diisopropyl-1-indenyl)ZrCl₂,dimethylsilanediylbis(2,4,6-trimethyl-1-indenyl)ZrCl₂,phenyl(methyl)silanediylbis(2-methyl-4,6-diisopropyl-1-indenyl)ZrCl₂,phenyl(methyl)silanediylbis(2,4,6-trimethyl-1-indenyl1)ZrCl₂,1,2-ethanediylbis(2-methyl-4,6-diisopropyl-1-indenyl)ZrCl₂,1,2-butanediylbis(2-methyl-4,6-diisopropyl-1-indenyl)ZrCl₂,dimethylsilanediylbis(2-methyl-4-ethyl-1-indenyl)ZrCl₂,dimethylsilanediylbis(2-methyl1-4-isopropyl-1-indenyl)ZrCl₂,dimethylsilanediylbis(2-methyl-4-t-butyl-1-indenyl)ZrCl₂,phenyl(methyl)silanediylbis(2-methyl-4-isopropyl-1-indenyl)ZrCl₂,dimethylsilanediylbis(2-ethyl-4-methyl-1-indenyl1)ZrCl₂,dimethylsilanediylbis(2,4-dimethyl-1-indenyl)ZrCl₂,dimethylsilanediylbis(2-methyl-4-ethyl-1-indenyl)ZrCl₂,dimethylsilanediylbis(2-methyl-α-acenaphth-1-indenyl)ZrCl₂,phenyl(methyl)silanediylbis(2-methyl-4,5-benzo-1-indenyl)ZrCl₂,phenyl(methyl)silanediylbis(2-methyl-α-acenaphth-1-indenyl)ZrCl₂1,2-ethanediylbis(2-methyl-4,5-benzo-1-indenyl)ZrCl₂,1,2-butanediylbis(2-methyl-4,5-benzo-1-indenyl)ZrCl₂,dimethylsilanediylbis(2-methyl-4,5-benzo-1-indenyl)ZrCl₂,1,2-butanediylbis(2-ethyl-4-phenyl1-1-indenyl)ZrCl₂,dimethylsilanediylbis(2-ethyl-4-phenyl-1-indenyl)ZrCl₂,dimethylsilanediylbis(2-methyl-5-isobutyl-1-indenyl)ZrCl₂,phenyl(methyl)silanediylbis(2-methyl-5-isobutyl-1-indenyl)ZrCl₂,dimethylsilanediylbis(2-methyl-5-t-butyl-1-indenyl)ZrCl₂, ordimethylsilanediylbis(2,5,6-trimethyl-1-indenyl)ZrCl₂,and thezirconocene of group Ia is (±)-phenyl(methyl)silyl(indenyl)₂ zirconiumdichloride, diphenylmethylene (9-fluorenyl)(cyclopentadienyl)zirconiumdichloride,phenyl(methyl)methylene(9-fluorenyl)(cyclopentadienyl)zirconiumdichloride, isopropylidene(9-fluorenyl)(cyclopentadienyl)-zirconiumdichloride, (±)-dimethylsilyl(2,3,5-trimethyl-1-cyclopentadienyl)₂zirconium dichloride, (±)-dimethylsilyl(indenyl)₂ zirconium dichloride,(±)-dimethylgermyl(indenyl)₂ zirconium dichloride,(±)-dimethylsilyl(indenyl)₂ zirconium dimethyl,(±)-phenyl(vinyl)silyl(indenyl)₂ zirconium dichloride, ##STR17##(±)-dimethylsilyl(2,4-dimethylcyclopentadienyl)₂ zirconium dichloride,(±)-isopropylidene(indenyl)₂ zirconium dichloride,(±)-dimethylsilyl(2-methyl-4,5,6,7-tetrahydro-1-indenyl)₂ zirconiumdichloride, (±)-ethylene(indenyl)₂ zirconium dichloride,(±)-methylene(3-t-butyl-1-cyclopentadienyl)₂ zirconium dichloride,(±)-dimethylsilyl(4,7-dimethyl-1-indenyl)₂ zirconium dichloride,(±)-dimethylsilyl(2-methyl-1-indenyl)₂ zirconium dichloride,(±)-phenyl(methyl)silyl(2-methyl-1-indenyl)zirconium dichloride,(±)-dimethylsilyl(2-ethyl-1-indenyl)₂ zirconium dichloride,(±)-dimethylsilyl(4,5-benzo-1-indenyl)₂ zirconium dichloride and(±)-dimethylsilyl(4-Phenyl-1-indenyl)₂ zirconium dichloride.
 6. Acatalyst system which comprises the combination of the metallocenemixture as claimed in claim 21 combined with an aluminoxane.
 7. Acatalyst system comprising the metallocene mixture as claimed in claim21 and an aluminoxane of the formula II ##STR18## for the linear typeand/or formula III ##STR19## for the cyclic type, in which the radicalsR in formulae II and III may be identical or different and are a C₁ -C₆alkyl group, a C₁ -C₆ fluoroalkyl group, a C₆ -C₁₈ aryl group, a C₁ -C₆fluoroaryl group or hydrogen and n is an integer from 0 to 50, or,instead of the aluminoxane, a mixture of the aluminoxane of the formulaII and/or the formula III with the AlR₃ compound.
 8. The catalyst asclaimed in claim 7, wherein the aluminoxane is methylaluminoxane.